Heat storage oxidation device and system for coal mine ultralow-concentration gas

Abstract

The invention discloses a coal mine ultra-low concentration gas heat storage oxidation device and system, which comprises a shell, a heat storage body and a direct combustion burner, an air chamber, a heat storage chamber and a combustion chamber are sequentially arranged in the shell from one side to the other side, the heat storage chamber is at least divided into two areas, the heat storage body is arranged in the heat storage chamber, the heat storage body is of a layered structure, and the direct combustion burner is arranged in the heat storage chamber. An upper heat storage layer, a middle heat storage layer and a lower heat storage layer are sequentially arranged from the side close to the combustion chamber to the side close to the air chamber. The upper heat storage layer is made of an inorganic nonmetal material, the high-temperature section of the upper heat storage layer is made of a high-aluminum refractory material, the medium-temperature section is made of a mullite material, and the low-temperature section is made of a cordierite material; the middle heat storage layer is made of a metal heat storage material; the lower heat storage layer is composed of a heat pipe array. The direct-combustion combustor is arranged on the side wall of the combustion chamber, and the gas inlet end of the direct-combustion combustor is used for being connected with a gas extraction pipeline; an air inlet and an air outlet are formed in the side wall of the air chamber.

Description

Technical Field

[0001] The present invention belongs to the technical field of efficient utilization of ultra-low concentration gas, and in particular relates to a thermal storage oxidation device and system for ultra-low concentration gas in coal mines. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Ultra-low concentration gas refers to coal mine gas with a methane concentration of less than 7%, which mainly exists in goafs and wind exhaust gas. The methane concentration of gas extracted by buried pipes is usually greater than 1%; wind exhaust gas is produced during the ventilation process of coal mine tunnels, and its methane concentration is generally less than 0.75%. Ultra-low concentration gas cannot be directly used for power generation, and the total amount is huge. Most of it is directly discharged into the air, which will produce a greenhouse effect.

[0004] Gas thermal storage oxidation technology is a commonly used method for treating ultra-low concentration gas. However, the ultra-low concentration gas generated in coal mines has large fluctuations in flow and concentration, resulting in poor working stability. During thermal storage oxidation, it is easy to cause incomplete combustion of gas and produce harmful substances such as CO. In addition, due to the low concentration of ultra-low concentration gas, the heat generated by combustion is small, and it is difficult to ensure the smooth operation of the system during the combustion process. In addition, the existing thermal storage body has poor temperature resistance and low thermal efficiency, especially when the working stability is poor, it is easy to lead to problems such as reduced service life, making it difficult to promote and apply.

[0005] In addition, the ultra-low concentration gas to be treated needs to be mixed evenly with air before entering the thermal storage oxidation device to ensure full oxidation inside the thermal storage oxidation device. However, the flow rate of ultra-low concentration gas is large and needs to be mixed with a large amount of air, which makes it difficult to ensure uniform mixing, further exacerbating the incomplete combustion of the gas. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a thermal storage oxidation device and system for ultra-low concentration gas in coal mines.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a thermal storage oxidation device for ultra-low concentration gas in coal mines, comprising a shell, a thermal storage body and a direct-fired burner, wherein:

[0009] The shell has a wind chamber, a heat storage chamber and a combustion chamber arranged in sequence from one side to the other, the heat storage chamber is divided into at least two areas, the heat storage body is arranged in the heat storage chamber, and the heat storage body is a layered structure, and an upper heat storage layer, a middle heat storage layer and a lower heat storage layer are arranged in sequence from the side close to the combustion chamber to the side close to the wind chamber;

[0010] The upper heat storage layer is made of inorganic non-metallic materials, the high temperature section is made of high-aluminum refractory materials, the medium temperature section is made of mullite materials, and the low temperature section is made of cordierite materials;

[0011] The middle heat storage layer is made of metal heat storage material; the lower heat storage layer is composed of heat pipe array;

[0012] The direct-fired burner is arranged on the side wall of the combustion chamber, and its air inlet end is used to connect with the gas extraction pipeline;

[0013] An air inlet and an air outlet are arranged on the side wall of the air chamber.

[0014] The heat storage chamber and combustion chamber adopt regular shapes, such as cylinder, rectangle, etc., to realize the independent division of multiple chambers of the heat storage body and the high-temperature oxidation combustion of ultra-low concentration gas. The heat storage chamber is divided into at least two areas, which are used for heating and oxidation of ultra-low concentration gas intake air and heat recovery and heat storage of high-temperature flue gas generated by combustion.

[0015] In a heat storage combustion device, the temperature in the combustion chamber is very high, and the temperature resistance of metal heat storage materials is relatively poor. Therefore, the heat storage material in the heat storage combustion furnace is generally made of high-temperature resistant materials such as ceramics. However, the thermal conductivity of ceramic materials is poor. When the high-temperature combustion gas is passed through the heat storage body for heat storage, due to the large gas flow rate, it is difficult for the ceramic heat storage body to quickly absorb the heat, resulting in a high air outlet temperature, making it difficult to effectively utilize the waste heat, resulting in heat waste. In addition, it is easy to cause the temperature of the ceramic heat storage body close to the combustion chamber to be very high, but the temperature of the ceramic heat storage body close to the wind chamber to be relatively low. When the gas-air mixture with a certain flow rate flows through the heat storage body in the low temperature zone, it is difficult to effectively preheat it, and then it is difficult to fully heat and burn when it flows through the high temperature section of the heat storage body, resulting in incomplete gas combustion.

[0016] In order to solve the above problems, the inventor designed the heat storage body into a three-layer structure, the upper heat storage layer is an inorganic non-metallic material, the high-temperature section is a high-aluminum refractory material, the middle section is a mullite material, and the low-temperature section is a cordierite material; the middle heat storage layer is a metal heat storage material; the lower heat storage layer is a heat pipe heat storage material.

[0017] The upper heat storage layer is closest to the combustion chamber. High-aluminum refractory materials are set in the high-temperature section. They have high refractoriness and good slag resistance, which can protect the heat storage body from high-temperature radiation, thereby helping to increase the overall service life of the heat storage body. The middle part uses mullite material, which has the advantages of high temperature resistance, oxidation resistance, high specific heat capacity, high heat storage efficiency, and low thermal expansion coefficient. It can quickly absorb and release heat, store more heat, and quickly cool down the high-temperature flue gas in the combustion chamber, protecting the cordierite heat storage body, metal heat storage body and heat pipe behind.

[0018] The cordierite thermal storage body has a small thermal expansion coefficient and has good corrosion resistance and resistance to rapid cooling and heating under working conditions below 1000°C. It can maintain structural stability under rapid temperature changes and is not easy to crack or deform. It can better maintain the structural stability of the entire thermal storage body to increase the service life of the thermal storage body.

[0019] Taking advantage of the characteristics of inorganic non-metallic material heat storage body, such as small volume, light weight, large specific surface area, high refractoriness, large heat transfer capacity, and straight airflow channel which makes the airflow resistance loss very small, it is more conducive to achieving low-oxygen combustion, making the furnace temperature uniform and the heat transfer rapid, greatly reducing oxidation loss and the generation of NOx gas, and significantly improving the environmental protection and energy-saving effects.

[0020] When the high-temperature flue gas flows through the upper heat storage layer, the temperature drops significantly. It is difficult to effectively absorb the waste heat in the flue gas by continuing to use ceramic heat storage bodies. Therefore, metal heat storage bodies are used in the middle heat storage layer. Although the heat storage performance of metal heat storage bodies is general and the high-temperature resistance is relatively large, it has a high thermal conductivity and can quickly absorb the waste heat in the flue gas, further reducing the temperature of the flue gas. In addition, metal heat storage bodies have price advantages and are easy to process.

[0021] A heat pipe structure is arranged at the position of the heat storage body near the air inlet. The thermal conductivity of the heat pipe far exceeds that of the metal, and the waste heat in the flue gas can be further absorbed and stored. Moreover, the metal heat storage body can transfer the heat to the heat pipe, so that the medium in the heat pipe is kept at a higher temperature.

[0022] When the gas + air mixed gas is introduced into the heat storage body after heat storage, it first flows through the heat pipe. Since the medium in the heat pipe is maintained at a relatively high temperature, the mixed gas can be preheated quickly. After flowing through the metal heat storage body, it can be preheated better. As a result, the mixed gas can basically reach the ignition point when flowing through the upper heat storage layer, and then the oxidation process is completed in the heat storage body, ensuring the safety of direct combustion of low-concentration gas in the combustion chamber.

[0023] Completing the oxidation process within the heat storage body can suppress the flame propagation speed and convert the explosion energy into stable combustion; it can prevent gas accumulation in the combustion chamber from causing excessive local gas concentration, and keep the remaining gas in the combustion chamber within a controllable combustion range.

[0024] Since the heat storage body generally adopts a honeycomb-shaped heat storage body with a high specific surface area, the contact between the heat storage body and the gas is more uniform and sufficient. When the gas can complete the oxidation process in the heat storage body, it can be said that the gas burns more completely in the heat storage combustion chamber.

[0025] In some embodiments, the thickness ratio of the upper heat storage layer, the middle heat storage layer, and the lower heat storage layer is 4-6:2-4:1-3.

[0026] Preferably, in the upper heat storage layer, the thickness ratio of the high temperature section, the medium temperature section and the low temperature section is 3-5:2-4:2-4.

[0027] In some embodiments, the heat pipe is arranged parallel to the middle heat storage layer to form a heat pipe array; or, the evaporation end of the heat pipe is inserted into or inserted into and passes through the middle heat storage layer, and the condensation end extends out of the middle heat storage layer.

[0028] When the evaporation end of the heat pipe is inserted into or inserted into and passes through the middle heat storage layer, in addition to quickly absorbing the waste heat in the flue gas, it can also better absorb the heat of the middle heat storage layer and even the upper heat storage layer, heat and evaporate the working fluid in the heat pipe, and make the temperature of the condensation end of the heat pipe higher, so as to achieve a good preheating effect on the incoming air.

[0029] In some embodiments, the heat pipe is a negative pressure heat pipe, a normal pressure heat pipe or a positive pressure heat pipe. The bottom of the thermal storage oxidation device belongs to the low temperature zone. By taking advantage of the small heat exchange temperature difference, high heat transfer coefficient, and low flow resistance of the heat pipe, the energy storage heat pipe is used for heat recovery, and the heat transfer heat pipe is used for heat exchange between the high temperature exhaust gas end and the low temperature intake air. The heat in the low temperature zone of the thermal storage oxidation device is quickly recovered, the exhaust air temperature is further reduced, and the intake air is quickly preheated.

[0030] The types of heat pipes are not limited to energy storage heat pipes and heat transfer heat pipes. The heat storage forms of the working fluid in the energy storage heat pipe include but are not limited to sensible heat, phase change, and chemical potential composite heat storage. The heat transfer working fluid of the heat transfer heat pipe includes but is not limited to organic, inorganic, metal, etc.

[0031] In some embodiments, a corundum blocking brick is provided on one side of the upper heat storage layer close to the combustion chamber to reduce the radiation of the high-temperature furnace to the heat storage body and increase the stacking stability of the heat storage body.

[0032] In some embodiments, the type of the upper heat storage layer includes but is not limited to a saddle ring type, a plate type, a honeycomb heat storage body, a heat storage ball or a heat storage tube.

[0033] In some embodiments, the middle heat storage layer includes, but is not limited to, a pressed type, a wire mesh type, a woven type, a rod type, a block type, or a spherical type. The middle temperature zone of the heat storage body utilizes the advantages of metal's high thermal conductivity, fast heat storage and release performance, good mechanical strength, low price, and convenient size and dimension adjustment according to needs to further improve the utilization efficiency of thermal energy.

[0034] In some embodiments, a high-temperature thermal bypass valve is provided on the side wall of the combustion chamber to discharge the extra heat generated by the self-balanced oxidation combustion of the gas through the high-temperature thermal bypass valve for heat reuse.

[0035] In some embodiments, the number of the heat storage chambers is an odd number greater than 1, and an air inlet, an air outlet and a purge air inlet are provided on the side wall of the air chamber.

[0036] Purge gas is a key link to ensure purification efficiency, equipment life and operational safety. By removing residues, diluting dangerous concentrations, and optimizing heat exchange and mixing effects, efficient treatment and energy recovery of organic waste gas are achieved.

[0037] In some embodiments, a secondary burner is provided in the wind chamber, heat storage chamber, combustion chamber or high-temperature heat bypass duct to add air thereto to ensure sufficient combustion of the gas. The location of the secondary burner is determined through simulation experiments.

[0038] In a second aspect, the present invention provides a thermal storage oxidation system for ultra-low concentration gas in coal mines, comprising the thermal storage oxidation device, a mixing device and a fan, wherein:

[0039] Inside the cylindrical shell of the mixing device, an expanding diameter guide tube, a first spoiler column, an air distribution ring tube, a reducing diameter guide tube and a second spoiler column are coaxially arranged in sequence from the air inlet end to the air outlet end, the small diameter end of the expanding diameter guide tube is connected to the air duct, and the large diameter end is fixed to the inner wall of the cylindrical shell;

[0040] The first spoiler column and the second spoiler column are arranged in the middle of the cylindrical shell;

[0041] The gas distribution ring pipe is connected to the gas pipeline, and the inner side of the gas distribution ring pipe is provided with gas distribution holes;

[0042] The large diameter end of the reduced diameter guide tube is fixed on the inner wall of the cylindrical shell, and the small diameter end extends toward the exhaust port;

[0043] The exhaust port is connected with the air inlet of the thermal storage oxidation device through a fan.

[0044] For large-flow gases, if an energy-consuming mechanical stirring device is used for mixing, a lot of energy will be consumed and it will be difficult to ensure uniform mixing.

[0045] In the mixing device of the present invention, each component is a fixed component, does not require energy consumption, and can mix a large amount of air with a large amount of ultra-low concentration gas. The functions of each component are as follows:

[0046] The expanded diameter guide tube is connected to the air duct and is used to guide part of the air to the edge of the cylindrical shell of the mixing device so that the air is quickly distributed over the entire cross section of the cylindrical shell;

[0047] A first spoiler column is arranged downstream of the large diameter end of the expanded diameter guide tube to disturb the air;

[0048] The air distribution holes are arranged on the inner side of the air distribution ring tube, so that the ultra-low concentration gas can be sprayed toward the inside of the cylindrical shell of the mixing device, and the arrangement of the air distribution ring tube reduces the flow cross section of this area. When the turbulent air flows through the reduced diameter, the flow velocity is accelerated, and the air flowing along the inner side of the cylindrical shell is also accelerated to converge and flow inward. The three factors of air flowing in different directions, air with different turbulence levels, and the acceleration of the air as a whole work together to accelerate the mixing of air and ultra-low concentration gas.

[0049] A reduced diameter guide tube is arranged downstream of the air distribution ring pipe to accelerate the mixed gas of air and ultra-low concentration gas, and a second spoiler column is used to further turbulently mix the accelerated mixed gas.

[0050] Through the above measures, the mixing uniformity of air and ultra-low concentration gas can be guaranteed without applying external energy. The evenly mixed gas is transported to the thermal storage oxidation device through the fan and evenly distributed in the thermal storage body.

[0051] If the air and ultra-low concentration gas are not mixed evenly, after the mixed gas enters the heat storage body, it will also cause uneven gas distribution and uneven air distribution in different parts of the heat storage body, making it difficult for the gas to be fully oxidized and producing harmful gases.

[0052] In some embodiments, the thermal storage oxidation device is connected to the waste heat utilization system through a high-temperature thermal bypass valve to provide heat to the outside.

[0053] In some embodiments, the air outlet of the air chamber is connected to an exhaust duct.

[0054] In some embodiments, the wind chamber is also connected to a purge air duct.

[0055] Valves are installed on the pipeline, and the valve types include but are not limited to lifting valves, rotary valves, butterfly valves, etc., to realize the functions of low-concentration gas inlet, outlet, and air chamber purging.

[0056] In some embodiments, the thermal storage oxidation device is a horizontal multi-chamber thermal storage oxidation device or a rotating multi-chamber thermal storage oxidation device.

[0057] If the comprehensive intake air concentration of the device is increased to 1.8%-3.0%, the comprehensive thermal efficiency will be increased to 90.0%, and the power consumption will be reduced by about 12.0%. It can solve the problem of efficient utilization of extracted gas below 3.0% and above 5% in coal mines, improve energy efficiency and include all extracted gas in CCER emission reduction. It can achieve the safety, high heat storage capacity, high thermal efficiency, high oxidation rate and high waste heat utilization capacity of large-flow gas thermal storage oxidation.

[0058] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0059] A direct-fired burner is arranged on the side wall of the combustion chamber. The direct-fired burner is connected to the extracted gas pipeline and has the functions of preheating before start-up and increasing the output power under normal working conditions. The normally operating combustion chamber is used as its stable combustion chamber to ensure that the gas combustion is fully stable, and more heat can be output to the outside, and sufficient heat can be provided to store heat in the heat storage body, so as to ensure the stable heat storage oxidation treatment of ultra-low concentration gas.

[0060] The heat storage body of the present invention is designed as a three-layer structure, the upper heat storage layer is an inorganic non-metallic material, the high temperature section is a high-aluminum refractory material, the middle section is a mullite material, and the low temperature section is a cordierite material; the middle heat storage layer is a metal heat storage material; the lower heat storage layer is a heat pipe heat storage material. This heat storage body can have good heat resistance, can quickly recover the waste heat in the high-temperature flue gas, reduce the exhaust temperature, and can also realize the rapid preheating of the incoming air. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0062] Figure 1 It is a schematic diagram of the front view structure of a five-chamber horizontal thermal storage oxidation device in an embodiment of the present invention;

[0063] Figure 2 is a schematic structural diagram of a horizontal thermal storage oxidation system in an embodiment of the present invention;

[0064] Figure 3 is a schematic structural diagram of a rotary thermal storage oxidation device in an embodiment of the present invention;

[0065] Figure 4 is a schematic structural diagram of a rotary thermal storage oxidation system in an embodiment of the present invention;

[0066] Figure 5 is a schematic diagram of the internal structure of a mixing device in an embodiment of the present invention;

[0067] Figure 6 Schematic diagram of the structure of the gas pipe in the embodiment of the present invention;

[0068] Figure 7 It is a simulation diagram of the thermal storage oxidation process in an embodiment of the present invention.

[0069] Among them, 1-wind chamber; 2-heat storage chamber; 3-combustion chamber; 4-second upper heat storage layer; 5-second middle heat storage layer; 6-second lower heat storage layer; 7-second secondary afterburner; 8-second high-temperature thermal bypass valve; 9-first upper heat storage layer; 10-first middle heat storage layer; 11-first lower heat storage layer; 12-first secondary afterburner; 13-first high-temperature thermal bypass valve; 14-direct-fired burner; 15-waste heat utilization system; 16-mixing device; 17-fan; 18-air duct; 19-expanding guide tube; 20-first spoiler column; 21-gas duct; 22-reducing guide tube; 23-second spoiler column; 24-exhaust duct; 25-air distribution ring pipe; 26-air distribution hole. DETAILED DESCRIPTION

[0070] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0071] The present invention will be further described below in conjunction with the embodiments.

[0072] Example 1

[0073] like Figure 1 As shown, a thermal storage oxidation device for ultra-low concentration gas in coal mines comprises a shell, a thermal storage body and a direct-fired burner, wherein:

[0074] The shell has a wind chamber 1, a heat storage chamber 2 and a combustion chamber 3 arranged in sequence from one side to the other. The heat storage chamber 2 is divided into at least two areas. The heat storage body is arranged in the heat storage chamber 2. The heat storage body is a layered structure. A first upper heat storage layer 9, a first middle heat storage layer 10 and a first lower heat storage layer 11 are arranged in sequence from the side close to the combustion chamber 3 to the side close to the wind chamber.

[0075] The first upper heat storage layer 9 is made of inorganic non-metallic material, the high temperature section is made of high-aluminum refractory material, the medium temperature section is made of mullite material, and the low temperature section is made of cordierite material;

[0076] The first middle heat storage layer 10 is a metal heat storage material; the first lower heat storage layer 11 is composed of a heat pipe array;

[0077] The direct-fired burner 14 is arranged on the side wall of the combustion chamber 3, and its air inlet end is used to be connected to the gas extraction pipeline;

[0078] An air inlet and an air outlet are arranged on the side wall of the air chamber 1 .

[0079] The heat storage chamber is divided into 5 chambers: heat storage chamber A4, B5, C6, D7, and E8. The five heat storage chambers have two inlets and two outlets and one cleaning, ensuring that the five heat storage chambers can circulate air intake, air outlet, and purge air.

[0080] The thickness ratio of the first upper thermal storage layer 9 , the first middle thermal storage layer 10 , and the first lower thermal storage layer 11 is 5:3:2.

[0081] In the first upper heat storage layer 9, the thickness ratio of the high temperature section, the medium temperature section and the low temperature section is 4:3:3.

[0082] The heat pipe is arranged parallel to the first middle heat storage layer 10 to form a heat pipe array; or, the evaporation end of the heat pipe is inserted into or inserted into and penetrates the middle heat storage layer, and the condensation end extends out of the first middle heat storage layer 10. The heat pipe is a negative pressure heat pipe, a normal pressure heat pipe or a positive pressure heat pipe.

[0083] The types of heat pipes are not limited to energy storage heat pipes and heat transfer heat pipes. The heat storage forms of the working fluid in the energy storage heat pipe include but are not limited to sensible heat, phase change, and chemical potential composite heat storage. The heat transfer working fluid of the heat transfer heat pipe includes but is not limited to organic, inorganic, metal, etc.

[0084] A corundum blocking brick is arranged on one side of the first upper heat storage layer 9 close to the combustion chamber 3 to reduce the radiation of the high-temperature furnace to the heat storage body and increase the stacking stability of the heat storage body.

[0085] The types of the first upper heat storage layer 9 include but are not limited to saddle ring type, plate type, honeycomb type heat storage body, heat storage ball or heat storage tube.

[0086] The types of the first middle heat storage layer 10 include but are not limited to pressed type, wire mesh type, woven type, rod type, block type or spherical type.

[0087] The wind chamber 1 of the low-concentration gas thermal storage oxidation device is provided with an air inlet duct, an air outlet duct and a purge duct. The air inlet duct is provided with an air inlet valve, the air outlet duct is provided with an air outlet valve, and the purge duct is provided with a purge valve.

[0088] The air supplementary combustion method is adopted to realize the complete combustion of gas. Multiple first and second supplementary burners 12 are set to avoid the situation that insufficient combustion air in the gas occurs when the gas concentration is increased to improve the thermal efficiency of the system. The first and second supplementary burners 12 can be set in the wind chamber 1, the heat storage chamber 2 or the combustion chamber 3, etc., and their positions are determined by simulation experiments, such as Figure 7 As shown, the position with high methane concentration is set as the supplementary combustion position.

[0089] The combustion chamber is provided with a first high-temperature thermal bypass valve 13 as a backup, so that the extra heat generated by the self-balanced oxidation combustion of the gas can be discharged through the thermal bypass valve for heat reuse.

[0090] A 5.0-15.0% extracted gas direct-fired burner 14 is added to the central oxidation zone of the combustion chamber. The direct-fired burner 14 has the functions of preheating at start-up and increasing the output power under normal working conditions.

[0091] like Figure 3 , Figure 5 and Figure 6 As shown, inside the cylindrical shell of the mixing device, an expanding diameter guide tube 19, a first spoiler column 20, an air distribution ring tube 25, a reducing diameter guide tube 22 and a second spoiler column 23 are coaxially arranged in sequence from the air inlet end to the air outlet end, the small diameter end of the expanding diameter guide tube 19 is connected to the air duct 18, and the large diameter end is fixed to the inner wall of the cylindrical shell;

[0092] The first spoiler column 20 and the second spoiler column 23 are arranged in the middle of the cylindrical shell;

[0093] The gas distribution ring pipe 25 is connected to the gas pipeline 21, and the inner side of the gas distribution ring pipe 25 is provided with gas distribution holes 26;

[0094] The large diameter end of the reduced diameter guide tube 22 is fixed on the inner wall of the cylindrical shell, and the small diameter end extends toward the exhaust port;

[0095] The exhaust port is connected to the air inlet of the thermal storage oxidation device through a fan 17 .

[0096] The thermal storage oxidation device is connected to the waste heat utilization system 15 through a high-temperature thermal bypass valve to provide heat to the outside.

[0097] The coal mine uses a thermal storage oxidation method for ultra-low concentration gas, as follows:

[0098] Step 1: First, the direct-fired burner 14 in the central oxidation zone uses the extracted gas with a concentration of 5.0-15.0% for direct combustion to preheat the combustion chamber. After the temperature of the combustion chamber rises to a certain temperature, the air outlet valves of the heat storage chambers A4 and B5 are opened. The high-temperature flue gas after combustion releases heat through the three layers of heat storage bodies in the two heat storage chambers and is discharged after the temperature is reduced. The heat storage bodies in the heat storage chambers A4 and B5 absorb heat and store a large amount of heat for heating in the next cycle.

[0099] Step 2: Perform the first cycle, open the air inlet valves of the heat storage chambers A4 and B5, and 1.5% low-concentration gas enters the heat storage chambers A4 and B5 under the action of the fan. The 1.5% low-concentration gas absorbs the heat of the heat storage body and heats up before entering the combustion chamber. The direct-fired burner 14 in the central oxidation zone of the combustion chamber uses 5.0-15.0% extracted gas for direct combustion to ensure that the combustion chamber always maintains a high temperature state. After entering the combustion chamber, the 1.5% low-concentration gas is further heated by the high-temperature flue gas directly burned, and then ignited. The ultra-low-concentration gas is oxidized in the combustion chamber to release heat. The high-temperature gas after combustion leaves the combustion chamber and enters the heat storage chambers C6 and D7, releasing heat. It is discharged after the temperature drops. The heat storage chambers C6 and D7 absorb the heat of the high-temperature flue gas and the temperature rises, which is used for heating in the next cycle. The heat storage chamber E8 is purged during this process to reduce the concentration of any residual gas to a safe level.

[0100] Step 3: After the above steps are completed, the inlet and outlet air and purge valves are switched to enter the second cycle. At this time, the regenerators C6 and D7 are inlet, the regenerator transfers heat to the 1.5% low-concentration gas, the fresh air purges the combustion chamber through the regenerator A4, and the regenerators B5 and E8 exhaust air to complete the regenerator energy storage.

[0101] Step 4: In the third cycle, air enters regenerators B5 and E8, air is discharged from regenerators A4 and D7, and regenerator C6 is purged.

[0102] Step 5, the fourth cycle, the regenerators A4 and D7 take in air, the regenerators C6 and E8 exhaust air, and the regenerator B5 is purged.

[0103] Step six, the fifth cycle, the regenerators C6 and E8 take in air, the regenerators A4 and B5 exhaust air, and the regenerator D7 is purged.

[0104] Step 7, the second cycle of step 2 begins to repeat the cycle process, and the process is continuously alternating. During the process, the first and second afterburners 12 replenish fresh air to avoid the occurrence of insufficient combustion air due to excessive gas concentration. The direct-fired burner 14 in the central oxidation zone uses 5.0-15.0% of the extracted gas for direct combustion to ensure that the combustion chamber remains at a high temperature, and at the same time the comprehensive intake air concentration is increased to 1.8%-3.0%.

[0105] Example 2

[0106] Take the rotary thermal storage oxidation device as an example, see Figure 2 As shown, the rotary RTO is mainly composed of a combustion chamber 3, a regenerator 2 and a wind chamber 1. The rotary furnace body is divided into 12 regenerators, and its functions are divided into 5 air inlet chambers (preheating zones), 5 air outlet chambers (cooling zones), 1 purge chamber and 1 isolation chamber.

[0107] The heat storage body is arranged in the heat storage chamber 2, and the heat storage body is a layered structure, and a second upper heat storage layer 4, a second middle heat storage layer 5 and a second lower heat storage layer 6 are arranged in sequence from the side close to the combustion chamber 3 to the side close to the wind chamber;

[0108] The second upper heat storage layer 4 is made of inorganic non-metallic material, the high temperature section is made of high-aluminum refractory material, the medium temperature section is made of mullite material, and the low temperature section is made of cordierite material;

[0109] The second middle heat storage layer 5 is made of metal heat storage material; the second lower heat storage layer 6 is made of heat pipes;

[0110] The thickness ratio of the second upper thermal storage layer 4 , the second middle thermal storage layer 5 , and the second lower thermal storage layer 6 is 5:3:2.

[0111] In the second upper heat storage layer 4, the thickness ratio of the high temperature section, the medium temperature section and the low temperature section is 4:3:3.

[0112] The heat pipe is arranged parallel to the second middle heat storage layer 5 to form a heat pipe array; or, the evaporation end of the heat pipe is inserted into or inserted into and passes through the middle heat storage layer, and the condensation end extends out of the second middle heat storage layer 5. The heat pipe is a negative pressure heat pipe, a normal pressure heat pipe or a positive pressure heat pipe.

[0113] The types of heat pipes are not limited to energy storage heat pipes and heat transfer heat pipes. The heat storage forms of the working fluid in the energy storage heat pipe include but are not limited to sensible heat, phase change, and chemical potential composite heat storage. The heat transfer working fluid of the heat transfer heat pipe includes but is not limited to organic, inorganic, metal, etc.

[0114] A corundum blocking brick is arranged on one side of the second upper heat storage layer 4 close to the combustion chamber 3 to reduce the radiation of the high-temperature furnace to the heat storage body and increase the stacking stability of the heat storage body.

[0115] The types of the second upper heat storage layer 4 include but are not limited to saddle ring type, plate type, honeycomb heat storage body, heat storage ball or heat storage tube.

[0116] The types of the second middle heat storage layer 5 include but are not limited to pressed type, wire mesh type, woven type, rod type, block type or spherical type.

[0117] The air supplementary combustion in the second combustion chamber is adopted to realize the complete combustion of gas, and multiple second and second supplementary burners 7 are arranged to avoid the situation that insufficient combustion air in the gas is caused by increasing the gas concentration to improve the system thermal efficiency. The second and second supplementary burners 7 can be arranged in the wind chamber, the heat storage chamber or the combustion chamber.

[0118] The combustion chamber is provided with a second high-temperature thermal bypass valve 8 as a backup, so that the extra heat generated by the self-balanced oxidation combustion of the gas can be discharged through the thermal bypass valve for heat reuse.

[0119] A 5.0-15.0% extracted gas direct-fired burner is installed in the central oxidation zone of the combustion chamber. The direct-fired burner has the functions of preheating during start-up and increasing the output power under normal operating conditions.

[0120] The device for mixing air and gas is the same as that in Example 1.

[0121] The coal mine uses a thermal storage oxidation method for ultra-low concentration gas, as follows:

[0122] Step 1: First, the direct-fired burner in the central oxidation zone uses 5.0-15.0% extracted gas for direct combustion to preheat the combustion chamber. After the temperature of the combustion chamber rises to a certain temperature, the high-temperature gas after combustion preheats the five heat storage chambers under the action of the distribution valve. The high-temperature gas is discharged after the temperature is reduced, and the three-layer heat storage body of the five heat storage chambers absorbs the heat of the high-temperature gas, stores it and uses it for the next cycle to heat 1.5% low-concentration gas. Fresh air is purged through the purge chamber to the combustion chamber.

[0123] Step 2: Under the action of the distribution valve, the 1.5% low-concentration gas enters the heat storage body of the first step for preheating. After the gas is preheated to a certain temperature, it enters the combustion chamber at the top. After entering the combustion chamber, the 1.5% low-concentration gas is further heated by the high-temperature flue gas directly burned, and then ignited, oxidized in the combustion chamber to release heat, and completely oxidized and decomposed. The purified high-temperature gas leaves the combustion chamber and enters the heat storage chamber, transferring heat to the heat storage body in the heat storage chamber, while the gas is cooled and discharged through the gas distributor. The ceramic heat storage body in the heat storage chamber absorbs heat and "stores" a large amount of heat (for heating the 1.5% low-concentration gas in the next cycle). This is repeated alternately, and the low-concentration gas is oxidized and decomposed in the combustion chamber. The direct-fired burner in the central oxidation zone uses 5.0-15.0% extracted gas for direct combustion to ensure that the combustion chamber remains at a high temperature. During this process, the high-temperature thermal bypass valve configured in the combustion chamber discharges the extra heat generated by the self-balanced oxidation combustion of the gas for heat reuse.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thermal storage oxidation device for ultra-low concentration gas in coal mines, characterized in that: It includes a shell, a heat storage body and a direct-fired burner, wherein: The shell has a wind chamber, a heat storage chamber and a combustion chamber arranged in sequence from one side to the other, the heat storage chamber is divided into at least two areas, the heat storage body is arranged in the heat storage chamber, and the heat storage body is a layered structure, and an upper heat storage layer, a middle heat storage layer and a lower heat storage layer are arranged in sequence from the side close to the combustion chamber to the side close to the wind chamber; The upper heat storage layer is made of inorganic non-metallic materials, the high temperature section is made of high-aluminum refractory materials, the medium temperature section is made of mullite materials, and the low temperature section is made of cordierite materials; The middle heat storage layer is made of metal heat storage material; the lower heat storage layer is composed of heat pipe array; The direct-fired burner is arranged on the side wall of the combustion chamber, and its air inlet end is used to connect with the gas extraction pipeline; An air inlet and an air outlet are arranged on the side wall of the air chamber.

2. The thermal storage oxidation device for ultra-low concentration coal mine gas according to claim 1 is characterized in that: The thickness ratio of the upper heat storage layer, the middle heat storage layer and the lower heat storage layer is 4-6:2-4:1-3; Preferably, in the upper heat storage layer, the thickness ratio of the high temperature section, the medium temperature section and the low temperature section is 3-5:2-4:2-4.

3. The thermal storage oxidation device for ultra-low concentration coal mine gas according to claim 1 is characterized in that: The heat pipe is arranged parallel to the middle heat storage layer to form a heat pipe array; or, the evaporation end of the heat pipe is inserted into or inserted into and penetrates the middle heat storage layer, and the condensation end extends out of the middle heat storage layer; Alternatively, the heat pipe is a negative pressure heat pipe, a normal pressure heat pipe or a positive pressure heat pipe.

4. The thermal storage oxidation device for ultra-low concentration coal mine gas according to claim 1 is characterized in that: A corundum retaining brick is arranged on one side of the upper heat storage layer close to the combustion chamber.

5. The thermal storage oxidation device for ultra-low concentration coal mine gas according to claim 1, characterized in that: The number of the heat storage chambers is an odd number greater than 1, and an air inlet, an air outlet and a purge air inlet are arranged on the side wall of the air chamber.

6. The thermal storage oxidation device for ultra-low concentration coal mine gas according to claim 1, characterized in that: A secondary afterburner is arranged in the wind chamber, heat storage chamber, combustion chamber or high-temperature heat bypass pipeline to replenish air therein.

7. A thermal storage oxidation system for ultra-low concentration gas in coal mines, characterized in that: It comprises the thermal storage oxidation device, the mixing device and the fan as described in any one of claims 1 to 6, wherein: Inside the cylindrical shell of the mixing device, an expanding diameter guide tube, a first spoiler column, an air distribution ring tube, a reducing diameter guide tube and a second spoiler column are coaxially arranged in sequence from the air inlet end to the air outlet end, the small diameter end of the expanding diameter guide tube is connected to the air duct, and the large diameter end is fixed to the inner wall of the cylindrical shell; The first spoiler column and the second spoiler column are arranged in the middle of the cylindrical shell; The gas distribution ring pipe is connected to the gas pipeline, and the inner side of the gas distribution ring pipe is provided with gas distribution holes; The large diameter end of the reduced diameter guide tube is fixed on the inner wall of the cylindrical shell, and the small diameter end extends toward the exhaust port; The exhaust port is connected with the air inlet of the thermal storage oxidation device through a fan.

8. The thermal storage oxidation system for ultra-low concentration coal mine gas according to claim 7 is characterized in that: The thermal storage oxidation device is connected to the waste heat utilization system through a high-temperature thermal bypass valve.

9. The thermal storage oxidation system for ultra-low concentration coal mine gas according to claim 7, characterized in that: The wind chamber is also connected to a purge air duct.

10. The thermal storage oxidation system for ultra-low concentration coal mine gas according to claim 7, characterized in that: The thermal storage oxidation device is a horizontal multi-chamber thermal storage oxidation device or a rotating multi-chamber thermal storage oxidation device.

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